The present embodiments generally pertain to heat exchangers utilized with gas turbine engines. More particularly, but not by way of limitation, the present embodiments relate to monolithic tube-in matrix heat exchangers which provide robust and redundant leak containment while allowing heat transfer between multiple tube flow circuits.
In a gas turbine engine, air is pressurized in a compressor and mixed with fuel in a combustor for generating hot combustion gases which flow downstream through turbine stages. A typical gas turbine engine generally possesses a forward end and an aft end with its several core or propulsion components positioned axially therebetween. An air inlet or intake is located at a forward end of the gas turbine engine. Moving toward the aft end, in order, the intake is followed by a compressor, a combustion chamber, and a turbine. It will be readily apparent from those skilled in the art that additional components may also be included in the engine, such as, for example, low-pressure and high-pressure compressors, and low-pressure and high-pressure turbines. This, however, is not an exhaustive list. In a typical turbo-prop gas turbine engine aircraft, turbine stages extract energy from the combustion gases to turn a turbo-propeller. In some embodiments, the propulsor may power one or more turbo-propellors (hereinafter, “turbo-prop”) in the case of some airplanes. In alternate embodiments, the propulsor may drive one or more turbo-propellers, embodied as rotors, for operation of a helicopter.
During operation, significant heat is generated by the high-pressure compressor which generates high temperature flow. It may be necessary to manage heat generation within the engine so as not to raise engine temperatures to unacceptable levels, which may cause engine failure. One method of doing this is by using bleed air to cool components. However, it may also be necessary to control the temperature of the compressor discharge air prior to such bleed air cooling other engine components.
In order to cool high pressure and temperature compressor discharge air, attempts have been made to utilize double-wall heat exchangers. However, such attempts have not been as successful as desired. Various shortcomings have been noted during the use of such heat exchangers where one bleed flow circuit operates at high temperature and high pressure concurrently. Due to the air gaps formed by outer walls that surround the inner walls or flow tubes, the heat transfer or thermal effectiveness of such double-wall exchangers is somewhat limited. Additionally, independent fluid flows may mix when structural failures occur. It would be desirable to increase the number of necessary failures in order to have the resultant undesirable mixing of fluids.
Additionally, alternative types of coolers, for example plate fin coolers, are susceptible to peel apart failures.
It would be desirable to provide a heat exchanger for two or more fluid flows to remain independent. It would also be desirable to decrease the likelihood of mixing of fluid flows due to failures in the heat exchanger by increasing the number of paths required for such failures. Additionally, it would be desirable to improve the thermal conductivity of the heat exchangers as compared to, for example, double-wall heat exchangers. It would further be desirable to provide a heat exchanger which meets these and other goals and which may be fabricated by additive manufacturing (three-dimensional printing) techniques.
The information included in this Background section of the specification, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not to be regarded subject matter by which the scope of the instant embodiments are to be bound.